Field of the Invention
The embodiments of the invention relate to electronic security devices, and more particularly, to a switch and filter for isolating an electronic device from external signals. Although embodiments of the invention are suitable for a wide scope of applications, it is particularly suitable for protecting an electronic device from nefarious data snooping when using third-party chargers.
Discussion of the Related Art
Portable electronic devices such as laptops and cell phones are ubiquitous in modern life. These devices commonly include a general purpose processor, memory, and rechargeable batteries for powering the device. The devices include a variety of physical connectivity options, generally including ports and plugs for connecting external devices such as peripherals and power supplies.
As electronic device become ever smaller, the manufacturers seek to minimize physical connectivity options to save space. In a recent development, a new connectivity option the USB Type-C connector (USB-C) combines traditional USB 2.0, USB 3.0, and power delivery. A complete discussion of the USB protocols, connectors, and specifications is available from the USB Implementers Forum, Inc. and available at www.USB.org/developer/docs the entirety of which is hereby incorporated by reference. The USB-C connector has been embraced by some laptop manufacturers such as Apple to provide a single connectivity option both charging and connecting data peripherals. In some computer models, Apple includes just a single port that is used for both charging the device and connecting external peripherals.
Users of portable electronic devices are prone to forget the charging cables for their devices or unexpectedly find themselves with a low battery and need to borrow a charger from another person. As the USB-C connector becomes more popular and is implemented on more devices, it is possible that the USB-C connector will become a de facto standard. In such cases it may be unlikely that a user would bring their personal charger when traveling and instead opt to use a charger provided by another such as their workplace, a conference room, a hotel room, etc.
However, because both power and data are transmitted over the same cable, potential security problems can arise when using a charger provided by another. For example, because data and power are transmitted over a single connector, a nefarious entity may provide free device charging, such as in an airport or hotel, and simultaneously use the data connection to compromise the data stored on the electronic device.
Traditionally, a user could protect their device from such an intrusion by refraining from connecting external peripherals from untrusted third parties. However, when power and data are transmitted over same connector it is impossible to selectively refrain from connecting external data sources when charging an electronic device. A potential solution could be to simply provide a cable or connector that lacks data connections and provides only power connections. Such a solution is unworkable, however, because the power supply and the electronic device often need to exchange certain messages over a data connection to initiate charging, specify the power parameters such as voltage and available current, and provide notification of when charging is complete. Thus, there is a need to provide protection from untrusted, third-party device chargers when using connectors that provide both power and data connectivity.